These DNA walkers are incredibly small -- just 4 nanometers -- but they bring together teams of computer scientists, chemical engineers and biologists to seed instructions directly into atomic structures.

The idea is that robots can be programmed to create new devices, or for testing. They could identify cancer cells, for instance, and then deliver the drugs to kill them.

In the latest experiment "staples" of DNA were given designated oligonucleotides at their ends, and the robot followed this like a trail of bread crumbs across a nanoscale field. Researchers in chemistry and biochemistry from Arizona State and the University of Michigan were also on the team.

Because DNA is the building block for the current molecular robots, and because there is so much money in curing disease, medical applications are being seen first for this new technology.

But the implications are not limited to medicine. Just about any chemical process could be done by nanoscale robots which would repeat actions in response to set stimuli the way a knitter works. Inorgranic as well as organic compounds could be created by robots that themselves are either organic or inorganic.

All sorts of boundaries are being crossed here. Between organic and inorganic. Between machines and living things. If a robot is built with DNA aren't we building life? If other building blocks are used is it a second-class robot, even if it's performing an equivalent task to an organic one? If you're building an organic construct is it really a robot?